Brandon was born the youngest of six sisters in Londonderry, Northern Ireland, and raised in Scotland.

After arriving in the U.S., she caught on at CBS Television City, working for Rod Serling, John Frankenheimer and Playhouse 90. During a writers strike, she met and married talent agent Paul Brandon, who helped her open Commercials Unlimited in 1970.

Operating in a male-dominated field, Brandon built up a client list of hundreds of actors. Her roster included Robert Duvall, Dennis Miller, Rita Wilson, Dennis Quaid, Loni Anderson, Bo Derek, Burt Reynolds, Charlie Sheen and Bernie Casey. Her company had close ties with entertainment management firm Baker Messina and represented its client, Tim Allen, for commercials for 35 years.

“Nobody I know was more intimidating, engaging, loyal and loving than Sonjia,” Allen said. “And damn, she was funny.”

Along with telling jokes, Brandon’s pursuits beyond dealmaking included dancing and running. She enjoyed trips to Las Vegas, where she competed in slot-machine tournaments with her sister, Nora.

“Sonjia was an important part of the Association of Talent Agents and served on the board for decades,” ATA executive director Karen Stuart said. “A brilliant and stunning businesswoman, she fought for women in the talent agency business and worked tirelessly within ATA to shine a light on the importance of the commercial business. In June 2018 the ATA Board recognized Sonjia’s dedication to the talent agency business and granted her a life-time membership in ATA. We will miss her.”

Along with her daughter, Brandon is survived by her son-in-law, Robby Scharf.